Dept. of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical Univ., 34469, Maslak, Istanbul, Turkey.
J Food Sci. 2013 Feb;78(2):E206-21. doi: 10.1111/1750-3841.12023. Epub 2013 Jan 16.
Spray drying of liposomes with conventional wall materials such as maltodextrins often yields nonfunctional powders, that is, liposomes break down during drying and rehydration. Electrostatically coating the surface of liposomes with a charged polymer prior to spray drying may help solve this problem. Anionic lecithin liposomes (approximately 400 nm) were coated with lower (approximately 500 kDa, LMW-C) or higher (approximately 900 kDa, HMW-C) molecular weight cationic chitosan using the layer-by-layer depositing method. Low (DE20, LMW-MD) or high molecular weight (DE2, HMW-MD) maltodextrin was added as wall material to facilitate spray drying. If surfaces of liposomes (1%) were completely covered with chitosan (0.4%), no bridging or depletion flocculation would occur, and mean particle diameters would be approximately 500 nm. If maltodextrins (20%) were added to uncoated liposomes, extensive liposomal breakdown would occur making the system unsuitable for spray drying. No such aggregation or breakdown was observed when maltodextrin was added to chitosan-coated liposomes. Size changed little or even decreased slightly depending on the molecular weight of maltodextrin added. Scanning electron microscopy images of powders containing chitosan-coated liposomes revealed that their morphologies depended on the type of maltodextrin added. Powders prepared with LMW-MD contained mostly spherical particles while HMW-MD powders contained particles with concavities and dents. Upon redispersion, coated liposomes yielded back dispersions with particle size distributions similar to the original ones, except for LMW-C coated samples that had been spray dried with HMW-MD which yielded aggregates (approximately 30 μm). Results show that coating of liposomes with an absorbing polymer allows them to be spray dried with conventional maltodextrin wall materials.
Liposomes have attracted considerable attention in the food and agricultural, biomedical industries for the delivery of functional components. However, maintaining their stability in aqueous dispersion represents a challenge for their commercialization. Spray drying may promise a solution to that problem. However, prior to this study spray drying of liposomes often led to the loss of structural integrity. Results of this study suggest that spray drying might be used to produce commercially feasible liposomal powders if proper combinations of adsorbing and nonadsorbing polymers are used in the liquid precursor system.
用常规壁材如麦芽糊精喷雾干燥脂质体往往会产生非功能性粉末，也就是说，脂质体在干燥和复水过程中会破裂。在喷雾干燥前，用带电荷的聚合物静电包覆脂质体表面，可能有助于解决这个问题。用层层沉积法用较低分子量（约 500 kDa，LMW-C）或较高分子量（约 900 kDa，HMW-C）阳离子壳聚糖对阴离子大豆卵磷脂脂质体（约 400nm）进行包覆。添加低分子量（DE20，LMW-MD）或高分子量（DE2，HMW-MD）麦芽糊精作为壁材以促进喷雾干燥。如果脂质体表面（1%）完全被壳聚糖（0.4%）覆盖，就不会发生桥联或耗尽絮凝，平均粒径约为 500nm。如果将麦芽糊精（20%）添加到未包覆的脂质体中，会发生广泛的脂质体破裂，使系统不适合喷雾干燥。然而，当将麦芽糊精添加到包覆的脂质体时，没有观察到这种聚集或破裂。根据添加的麦芽糊精的分子量，粒径变化很小甚至略有减小。含有壳聚糖包覆脂质体的粉末的扫描电子显微镜图像表明，它们的形态取决于添加的麦芽糊精的类型。用 LMW-MD 制备的粉末主要包含球形颗粒，而 HMW-MD 粉末则包含具有凹痕和凹痕的颗粒。再分散时，包覆的脂质体产生的再分散体的粒径分布与原始粒径分布相似，除了用 HMW-MD 喷雾干燥的 LMW-C 包覆样品，其产生的聚集体（约 30μm）。结果表明，用吸收聚合物包覆脂质体可以使它们与常规麦芽糊精壁材一起喷雾干燥。
脂质体在食品和农业、生物医药行业中作为功能性成分的递送载体受到了广泛关注。然而，在水相分散体中保持其稳定性是其商业化的一个挑战。喷雾干燥可能是解决这个问题的一种方法。然而，在这项研究之前，脂质体的喷雾干燥往往导致结构完整性的丧失。这项研究的结果表明，如果在液体前体系统中使用适当的吸附和非吸附聚合物组合，喷雾干燥可能用于生产商业上可行的脂质体粉末。
